import Foundation

@available(iOS 15.0, *)
final class MopidyEventStream {
    private var session: URLSession?
    private var task: URLSessionDataTask?
    private let onTrackChanged: () -> Void
    private let onVolumeChanged: (Int) -> Void

    private let host: String
    private let password: String

    init(host: String,
         password: String,
         onTrackChanged: @escaping () -> Void,
         onVolumeChanged: @escaping (Int) -> Void)
    {
        self.host = host
        self.password = password
        self.onTrackChanged = onTrackChanged
        self.onVolumeChanged = onVolumeChanged

        let config = URLSessionConfiguration.default
        config.timeoutIntervalForRequest = 300
        config.timeoutIntervalForResource = 3600
        self.session = URLSession(configuration: config)
    }

    func connect() {
        guard let url = URL(string: "http://\(host):6680/mopidy/events") else { return }
        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.setValue("text/event-stream", forHTTPHeaderField: "Accept")
        request.setValue("application/json", forHTTPHeaderField: "Content-Type")
        self.task = session?.dataTask(with: request) { [weak self] data, response, error in
            guard let self = self, let data = data else { return }
            if let text = String(data: data, encoding: .utf8) {
                self.parseEvents(text)
            }
        }
        task?.resume()
    }

    func disconnect() {
        task?.cancel()
        session?.finishTasksAndInvalidate()
    }

    private func parseEvents(_ text: String) {
        for line in text.components(separatedBy: "\n") {
            if line.hasPrefix("event:") && line.contains("tracklistchanged") {
                onTrackChanged()
            }
            if line.hasPrefix("event:") && line.contains("volumechanged") {
                // volume data would follow in subsequent data: lines
            }
        }
    }
}